159 lines
4.3 KiB
Perl
159 lines
4.3 KiB
Perl
#!/usr/bin/perl
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=head1 NAME
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loadcheck
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=head1 DESCRIPTION
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Only takes email transactions if the system load is at or below a
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specified level.
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If this is running on a system that provides /kern/loadavg or
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/proc/loadavg it will be used instead of the 'uptime' command.
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Once a load value is determined, it is cached for a period of time.
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See the cache_time below.
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Since fork/exec is expensive in perl, if using the 'uptime' method,
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use cache_time to avoid increasing your load on every connection.
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=head1 CONFIG
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max_load
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This is the 1 minute system load where we won't take transactions
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if our load is higher than this value. (Default: 7)
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cache_time
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A recently determined load value will be cached and used for the
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assigned number of seconds. (Default: 10)
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uptime
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The path to the command 'uptime' if different than the default.
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(Default: /usr/bin/uptime)
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Example:
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loadcheck cache_time 30
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loadcheck max_load 7 uptime /usr/bin/uptime
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=head1 SEE ALSO
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Original version: http://www.nntp.perl.org/group/perl.qpsmtpd/2006/01/msg4422.html
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Variant with caching: http://www.nntp.perl.org/group/perl.qpsmtpd/2006/03/msg4710.html
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Steve Kemp's announcement of an alternate load limiter: http://www.nntp.perl.org/group/perl.qpsmtpd/2008/03/msg7814.html
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=head1 AUTHOR
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Written by Peter Eisch <peter@boku.net>.
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=head1 CHANGES
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v0.03 - msimerson - 2014-03-21
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* refactored "find the way to get load avg" out of loadcheck (every
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connection) into get_load_method which is run in register. If we can't
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get the load average, don't register the hook.
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* added BSD::getloadavg method (tested on FreeBSD)
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v0.02 - github@rsiddall - resurrected from list archives
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=cut
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my $VERSION = 0.03;
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sub register {
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my ($self, $qp, @args) = @_;
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$self->{_args} = { @args };
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$self->{_args}{max_load} ||= 7;
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$self->{_args}{uptime} ||= '/usr/bin/uptime';
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$self->{_args}{cache_time} ||= 10;
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$self->{_load} = -1;
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$self->{_time} = 0;
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$self->{_method} = $self->get_load_method();
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# only register the hook if we can measure load
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if (ref $self->{_method} eq 'CODE') {
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$self->register_hook("connect", "loadcheck");
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}
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}
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sub loadcheck {
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my ($self, $transaction) = @_;
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if (time() > ($self->{_time} + $self->{_args}{cache_time})) {
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# cache value expired, update
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$self->{_method}->();
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$self->{_time} = time();
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};
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if ($self->{_load} > $self->{_args}{max_load}) {
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$self->log(LOGERROR, "local load too high: $self->{_load}");
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return DENYSOFT, "Server load too high, please try again later.";
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}
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return DECLINED, "continuing with load: $self->{_load}";
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}
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sub get_load_method {
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my ($self) = @_;
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eval "use BSD::getloadavg;";
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if (!$@) {
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return sub {
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require BSD::getloadavg;
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$self->{_load} = (getloadavg())[0];
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$self->log(LOGDEBUG, "BSD::getloadavg reported: $self->{_load}");
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}
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}
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if (-r '/kern/loadavg') { # *BSD
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return sub {
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open(LD, '<', "/kern/loadavg"); # contains fix-point scaling value
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my $res = <LD>;
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close LD;
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my @vals = split(/ /, $res);
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$self->{_load} = ($vals[0] / $vals[3]);
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$self->log(LOGDEBUG, "/kern/loadavg reported: $self->{_load}");
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}
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}
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if (-r '/proc/loadavg') { # *inux
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return sub {
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open(LD, "<", "/proc/loadavg"); # contains decimal value
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my $res = <LD>; # contains fix-point scaling value
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close LD;
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$self->{_load} = (split(/ /, $res))[0];
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$self->log(LOGDEBUG, "/proc/loadavg reported: $self->{_load}");
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}
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}
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if (-x $self->{_args}{uptime}) {
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return sub {
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# the various formats returned:
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# 10:33AM up 2:06, 1 user, load averages: 6.55, 3.76, 2.48
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# 12:29am 2 users, load average: 0.05, 0.05, 0.06
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# 12:30am up 5 days, 12:43, 1 user, load average: 0.00, 0.00, 0.00
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my $res = `$self->{_args}{uptime}`;
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if ($res =~ /aver\S+: (\d+\.\d+)/) {
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$self->{_load} = $1;
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$self->log(LOGDEBUG, "$self->{_args}{uptime} reported: $self->{_load}");
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}
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}
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}
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$self->log(LOGERROR, "unable to acquire system load");
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return;
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}
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